Dorsal rhizotomy

A major side-effect of morphine is respiratory depression. Opiates are believed to cause this effect via actions in brainstem nuclei, fi receptor immunoreactivity and mRNA were detected in neurons of the nucleus of the solitary tract, nucleus ambiguous, and parabrachial nucleus. mRNA was detected in the bed nucleus of the stria terminalis which projects to the nucleus of the solitary tract, fi receptor immunoreactivity is found in the nucleus of the solitary tract and dorsal rhizotomy reduced receptor immunoreactivity in the nucleus suggesting a presynaptic localization of the receptor. 

Ultrastructural studies showed S receptor immunoreactivity was presynaptically localized to sensory inputs to the spinal cord [48]. Dorsal rhizotomy caused a dramatic decrease in <5 receptor immunoreactivity in spinal cord and <5 receptors were also expressed in the peripheral ganglia which send inputs to the spinal cord. These findings support the notion that <5 receptors are presynaptic to sensory inputs and are involved in the presynaptic inhibition of the release of transmitters involved in mediating nociceptive transmission. 

Soliman IE, Park TS, Berkelhamer MC. Transient paralysis after intrathecal bolus of baclofen for the treatment of post-selective dorsal rhizotomy pain in children. Anesth Analg 1999 89(5) 1233-5. 

In a smaller prospective, open, uncontrolled study, 12 children (3-6 years of age) were given either intermittent intrathecal morphine 5 pg/kg qds or a continuous infusion of a mixture of bupivacaine (40 pg/kg/hour) and morphine (0.6 pg/kg/hour) for intense postoperative pain after selective dorsal rhizotomy (35). The bupivacaine/ morphine mixture provided better analgesia with fewer adverse effects. The incidence of pruritus was 83% with morphine compared with 33% with bupivacaine/mor-phine. Otherwise the adverse effects were similar. 

Hesselgard K, Stromblad LG, Reinstrup P. Morphine with or without a local anaesthetic for postoperative intrathecal pain treatment after selective dorsal rhizotomy in children. Paediatr Anaesth 2001 ll(l) 75-9. 

Foschini, D.R., Kestler, A.M., Egger, M.D. and Crockett, D.P. (1994) The up-regulation of trkA and trkB in dorsal column astrocytes following dorsal rhizotomy. Neurosci. Lett. 169 21-24. 

Ninkovic, M., Hunt, S. P., and Kelly, J. S., 1981, Effect of dorsal rhizotomy on the autoradiographic distribution of opiate and neurotensin receptors and neurotensin-like immunoreactivity within the rat spinal cord. Brain Res., 230 111-119. 

When systemic or topical pharmacotherapy and other non-invasive approaches provide inadequate relief in patients with NP, interventional approaches may be used, including sympathetic blockade with local anesthetics, intraspinal drug delivery, spinal cord stimulation, peripheral subcutaneous nerve stimulation, or stimulation of specific central nervous system structures, and various neuroablative procedures (e.g. dorsal rhizotomy, neurolytic nerve block, intracranial lesioning). Neuroablative procedures are not reversible and should be reserved for carefully and properly selected patients with intractable pain. 

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